Thermal transport of solid polymers and polymer blends

A grand challenge in designing polymeric materials is to tune their properties by macromolecular engineering. Here, applications of polymers are often hindered by their low thermal conductivity k. While low k values are highly desirable for thermoelectric materials, they create severe problems when used under the high temperature conditions. Going from the polymers dictated by weak Van der Waals to hydrogen-bonded interactions, k varies between 0.1-0.4 W/Km. Using molecular dynamics simulations, we study thermal transport and its links to the elastic response of polymers and polymer blends in their solid states. We find that there exists a maximum attainable stiffness, thus providing an upper bound of k for solid polymers. The specific chemical structures and the glass transition temperature play no role in controlling k, especially when the microscopic interaction is hydrogen bonded. These results are consistent with the minimum thermal conductivity model and existing experiments.

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